Mechanical keys in modern portable devices can serve various purposes, such as a keyboard, for volume control, screen lock and others. Usually in devices with touch screens the mechanical keys serve a secondary purpose and are positioned on the edges of the device. The side keys are usually coupled to the printed circuit board (PCB) in order to perform their functions. The mechanical keys provide a tactile feedback different from a touch surface, so in some cases they can be preferable—cases like when a user cannot see the display of the device but wishes to give quick commands, for example change volume while the mobile phone is in the pocket.